The operation was coordinated by the National Crime Agency and involved 45 police forces across England, Wales, Scotland and Northern Ireland.

More than 400 children across the UK have been safeguarded.

Some of those arrested had unsupervised access to children in the course of their work. They include doctors, teachers, scout leaders, care workers and former police officers.

Of the 660, 39 people were Registered Sex Offenders but the NCA said the majority of those arrested had not previously come to law enforcement’s attention.

NCA Deputy Director General Phil Gormley said: “The operation targeted people accessing indecent images of children online. It has stayed covert till today in order to protect children, identify offenders and secure evidence.

“The NCA and its partners are not revealing the methods they used to track down suspects so that they can use the same tactics again in the future.

“Charging decisions are awaited in most cases because of ongoing enquiries but so far charges brought range from possessing indecent images of children to serious sexual assault.

“This is the first time the UK has had the capability to coordinate a single targeted operation of this nature. Over the past six months we have seen unprecedented levels of cooperation to deliver this result.”

Chief Constable Simon Bailey, the National Policing Lead for Child Protection and Abuse Investigations, said: “Sexual abuse is a complex crime taking many forms. “ The vast majority of forces around England and Wales are dealing with an unprecedented increase in the number of reports of sexual abuse of children.

“Forces are investigating exploitation of children and young people by groups and gangs, non-recent abuse including large scale investigations into abuse in institutions over many years and sexual abuse by parents and family members.

“During this operation, we’ve targeted offenders accessing child abuse images. “ Police must continue to use a range of investigative techniques targeting all forms of abuse if we going to protect children and bring offenders to justice.

“Chief officers are committed to use all the tools available to them because nothing is more important in policing than protecting vulnerable people”.